对于任何来这里寻找Create React App项目答案的人，你的变量名应该以REACT_APP_开头

更多信息请点击:https://facebook.github.io/create-react-app/docs/adding-custom-environment-variables

使用节点进程的最佳和最简单的方法。你的typescript项目中的env是首先用tsc编译，然后用node提供你的env var运行编译后的javascript文件。ts是你想要的输出目录也是编译文件的名称，我使用dist作为输出目录和index.js为例):

cd my-typescriptproject
tsc
NODE_ENV=test node ./dist/index.js

对于任何来这里寻找Create React App项目答案的人，你的变量名应该以REACT_APP_开头

更多信息请点击:https://facebook.github.io/create-react-app/docs/adding-custom-environment-variables

您可以为此使用类型断言

Sometimes you’ll end up in a situation where you’ll know more about a value than TypeScript does. Usually this will happen when you know the type of some entity could be more specific than its current type. Type assertions are a way to tell the compiler “trust me, I know what I’m doing.” A type assertion is like a type cast in other languages, but performs no special checking or restructuring of data. It has no runtime impact, and is used purely by the compiler. TypeScript assumes that you, the programmer, have performed any special checks that you need.

例子

const nodeEnv: string = (process.env.NODE_ENV as string);
console.log(nodeEnv);

或者，您可能会发现像env-var这样的库更适合这个特定的目的——

在node.js中使用正确类型加载和清除环境变量的解决方案

执行typescript最新版本后:

NPM install——save @types/node

你可以使用过程。env直接。

console.log（process.env[“NODE_ENV”]）

如果您设置了NODE_ENV，您将看到预期的结果。

我写了一个模块来简化它。它没有依赖关系，所以是相当轻量级的。它也适用于dotenv，您可以传递一个自定义进程。Env到Env .from函数，如果需要的话。

在一些回答中已经提到了它，但这里有一个例子:

使用yarn/npm安装:

npm install env-var --save

然后读取变量:

import * as env from 'env-var'

// Read NODE_ENV and verify that:
// 1) it is set using the required() function
// 2) it is either 'dev' or 'prod'
// 3) throw a runtime exception if conditions #1 or #2 fail
const environment = env.get('NODE_ENV').required().asEnum(['dev', 'prod'])

// Intellisense will suggest 'dev' or 'prod'
if (environment === 'dev') {
  console.log('yep, this is dev')
} else {
  console.log('looks like this is prod')
}

或另一个:

import { get } from 'env-var'

// Read the GitHub token. It could be undefined
const githubToken = get('GITHUB_TOKEN').asString()

// Read MAX_CONCURRENCY, or default to 5. Throw an error if it's
// not set to a positive integer value
const concurrencyLimit = get('MAX_CONCURRENCY').default(5).asIntPositive()

function callGitApi (token: string, concurrency: number) { /* implementation */ }

// TS Error: Argument of type 'string | undefined' is not assignable to
// parameter of type 'string'.
callGitApi(githubToken, concurrencyLimit)